Research On The Key Techniques Of Chipless Tag Sensors

Chipless tag sensor is using the EM wave echos' characters to detect the changes of environment and ID information.That is a new kind of sensor.The key techniques are urgent to be solved.In this thesis,The key techniques of chipless tag sensor which are the chipless RFID technology,chipless RFID sensing technology,chipless RFID detection technology are deeply studied,then a chipless temperature threshold sensor with 16bits encoding capacity is designed and implemented based on the key techniques.There are 4 missions which have been finished in this thesis:1.In the aspect of chipless RFID technology,the coding technique is in frequency domain.Starting from the simple structure of 'I-shaped' slot resonators,the 12bits tag is designed.In order to improve the capacity of coding bits,method of dual-polarized frequency band multiplexing is used to design a 16bits tag based on 'U-shaped' slot resonators.In order to enlarge coding densities,tag in compact size with 20bits coding capacity based on'arc-shaped' slot resonators is realized.From experimental results,by removing resonators or making short circuit patches on resonators can realize the reconstruction of tags.These tags can solve the problems which are large size,few coding bits in today's chpless RFID tag.2.In the aspect of chipless sensing technology,we systematically study the designing methods of low costs chipless sensor's structure and finally select the planar resonant element—Single Split Ring Resonator(SSRR)which is left-handed materials' resonant unit.Simulate the influence on resonant characteristics by structure parameters and compare with the simulation results,square SSRR are the best to be sensor's resonant structure.The temperature threshold sensor model is established.Different loading modes of the sensitive materials on the resonant structure are simulated,and the influences are compared.That provides a theoretical support for the design of high-sensitivity chipless sensor.3.In the aspect of chipless RFID detection technology,the key components of the detection system-broadband antenna are studied.Three planar antennas with wide bandwidth and good radiation characteristics are designed.The experimental results show that the antennas designed in this thesis meet the requirements of chipless tags and chpless sensors also designed in this thesis.4.A chpless temperature threshold sensor with 16bits coding capacity is designed.The coding part is based on 'arc-shaped' slot resonators,the sensitive material choose phenanthrene which is easily prepared.Experimental platform which is to test the chipless tag sensor is established.The experimental results show that the tag can identify the coding information correctly when the temperature changes and can accurately realize the threshold detection of temperature over 75?.